Over the generations, ancestors evolved different allele frequencies due to recurring natural selection. In fact, natural selection and mutation were considered the main hypotheses for the sickle gene cell. However, those hypotheses limit in explaining the entirety for the frequency of the HbS allele in human populations around the globe. The complex relationship between the HbS allele frequencies and the level of malaria prevalence support the malaria hypothesis at a global scale and further demonstrate why adaptation or natural selection alone cannot be the factor in explaining allele frequencies. According to Piel et. al. (2010), HbS, known as the sickle hemoglobin, is “a structural variant of normal adult hemoglobin” (p. 2). Piet et al.
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Livingstone presents the linguistic evidence for migration patterns over generations, which gives more support on the malaria hypothesis. Because of the common ancestries, languages are genetically related and possess different conditions for each groups based on their geographic regions. For example, Livingstone (1958) noted that Gambia and Sierra Leone has the highest frequencies of the sickle gene cell (p. 546). The Mande people moved in large numbers and seemed to introduce the particular gene into parts of Africa (Livingstone, 1958, p. 547). This large-scale migration led to higher frequencies of the sickle cell traits, which lends evidence about the HbS allele frequency variation. The linguistic evidence supports the West African HbS allele frequency variation because the migration pattern shows the spread of the selective advantage of the sickle cell gene. The environmental variation matters a lot especially for this case as language gives significant biological influence on the human populations. In addition, cultural development based on archeological evidence further explains how various adoption and geographic spread of agriculture technology caused exposure of high frequencies in human populations. The rice cultivation exemplifies gene flow, as it was responsible for the spread of the sickle cell gene in West Africa. According to Livingstone (1958), the relationship between the spread of the agriculture by diffusion and its frequencies exposed human populations to the parasites (p. 553). As human populations grew over time, the environmental change resulted in the “adaptation of several species of the Anopheles gambiae to human habitations and the adaptation of many parasites to man as their host” (Livingstone, 1958, p. 556). The adaptation is probably from the agricultural technology
Livingstone presents the linguistic evidence for migration patterns over generations, which gives more support on the malaria hypothesis. Because of the common ancestries, languages are genetically related and possess different conditions for each groups based on their geographic regions. For example, Livingstone (1958) noted that Gambia and Sierra Leone has the highest frequencies of the sickle gene cell (p. 546). The Mande people moved in large numbers and seemed to introduce the particular gene into parts of Africa (Livingstone, 1958, p. 547). This large-scale migration led to higher frequencies of the sickle cell traits, which lends evidence about the HbS allele frequency variation. The linguistic evidence supports the West African HbS allele frequency variation because the migration pattern shows the spread of the selective advantage of the sickle cell gene. The environmental variation matters a lot especially for this case as language gives significant biological influence on the human populations. In addition, cultural development based on archeological evidence further explains how various adoption and geographic spread of agriculture technology caused exposure of high frequencies in human populations. The rice cultivation exemplifies gene flow, as it was responsible for the spread of the sickle cell gene in West Africa. According to Livingstone (1958), the relationship between the spread of the agriculture by diffusion and its frequencies exposed human populations to the parasites (p. 553). As human populations grew over time, the environmental change resulted in the “adaptation of several species of the Anopheles gambiae to human habitations and the adaptation of many parasites to man as their host” (Livingstone, 1958, p. 556). The adaptation is probably from the agricultural technology